RE: green-card problem when using hugs

[Sigbjorn Finne (Intl Vendor)]

Nancy Day <[EMAIL PROTECTED]> writes: 
> 
> Hi --
> 
> I've been using green-card 2.0 with hugs version March 1999 (990319).
> The .hs file that green-card generates imports the Prelude
> qualified but uses the monad combinators (return, >>=) unqualified.
> It's pretty easy to work around this problem, but it would be
> good to fix it in the distribution.
> 

Hi,

I'm guessing you're using GreenCard to process something like
the following:

  foo$ cat sin.gc
  module Sin where

  import qualified Prelude
  import StdDIS

  %fun sin :: Float -> Float
  foo$ 

and it is failing..?

Yes, ideally, GreenCard should be able to handle that without
incident, but it's a preprocessor and mostly unaware of the
facilities of the Haskell module system. 

I don't propose to fix this, since Haskell98 goes a long way
towards solving the underlying problem with its lazy reporting
of name clashes, i.e., make the Prelude import unqualified and
you *should* be OK...at least if you're using a Haskell98
compliant system.

Neither ghc-4.02 nor the hugs98 snapshot (990319) I've got
handles this correctly though, i.e., the following isn't
accepted

  module Sin where

  sin :: Float -> Float
  sin x = x

but should be with my interpretation of the relevant sections
of the H98 report - both mentions of 'sin' can be unambiguously
resolved.

I've fixed this in the development sources for ghc, but, for now,
you may just want to use "hiding" instead of "qualified" in
your GC spec.

Thanks for the (indirect!) bug report.

--sigbjorn